GB321759A - Improvements in and relating to thermionic amplifiers - Google Patents

Abstract

321,759. Ryall, L. E. Sept. 11, 1928. Multi-way amplifying systems.-A number of lines A - - D and associated 2-wire and/or 4-wire amplifiers are associated with a common circuit in such a way that currents incoming over one line are repeated in amplified form over the other lines only. The common circuit comprises differential transformers 45, 53, one for each line. The balance terminals of each transformer are connected to a network balancing the rest of the common circuit and the line terminals are connected in a series or parallel circuit including the other transformers. To enable standard networks to be employed, resistances may be connected across the line terminals where the transformers are in series, or in series with the line terminals where they are in parallel. The primary windings are coupled to the lines (via in-amplifiers, not shown, in the case of the 4-wire circuits), and the mid-points of the secondaries are coupled to the input circuits of the amplifiers 41. Alternatively the common circuit may be associated in a similar manner with the output side of the amplifiers, with the intervalve circuits, or, according to the Provisional Specification, with the line side of the transformers 49. Local telephone circuits without amplifiers may be coupled to the common circuit.